Adjustable traverse control for surface grinder

ABSTRACT

The stroke of reciprocation of a workpiece carrying table for a surface grinder is controlled by a pair of stationary control elements connected with the power drive for the table and adjustable in the directions of table motion, and a cooperating element fixed on the table. Proximity responsive control systems are disclosed. In one, each stationary element comprises a reed switch normally held closed by a magnet, and an iron vane carried by the table comes between the magnet and the reed switch at the end of the stroke.

1451 June 20, 1972 United States Patent Berkholcs [s41 ADJUSTABLE TRAVERSE CONTROL 2,349,602 5/1944 Baldenhofer........................

FOR SURFACE GRINDER 2,659,314 11/1953 3,281,994 11/1966 Robinson.....

[ lnvemofl GordonBerkholcs, BloominstomMinn- 2,416,861 3/1947 [73] Assignee: Continental Machines, lnc., Savage, Minn.

[22] Filed: Aprll 21, 1970 Primary Examiner-Donald G. Kelly Attorney-1m Milton Jones ABSTRACT The stroke of reciprocation of a workpiece carrying table for a surface grinder is conu'olled by a pair of stationary control ele- [21] App]. No.: 30,520

[52] U.S.Cl. [5]] Int 1324]) 47/06 .5 H92, 233, 34 R, 34 C, 34 D S merits connected with the power drive for the table and ad- Field of h justable in the directions of table motion, and a cooperating 233 element fixed on the table. Proximity responsive control systems are disclosed. In one, each stationary element com- 51/34 H, 34 J, 59 R, 92 R, 122, 231

[56] Remnces Cited prises a reed switch normally held closed by a magnet, and an UNITED STATES PATENTS iron vane carried by the table comes between the magnet and the reed switch at the end of the stroke. 1,854,610 4/1932 1,899,362 2/1933 7 Claim, 13 Drawing figures ....5l/233 X 51/233 X Konmg Stratton................

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PATENTEDJUHO I972 SHEET S 0? 7 NVENTOR Gal-flan .E rkhulcs BY A-r'roa EY PKTENTE'BJUHO m2 3 670,457 sum 6 BF 7 FIG.7.

SOLENOID A m X -FEG3] SOLENOlD B FILTER TABLE SPEED VALVE |8\% SOLENOID- A SOLENOID B i |n.J- Q

NVENTOR Gar/inn .EerkZwZss BY AT'rorz EY ADJUSTABLE TRAVERSE CONTROL FOR SURFACE GRINDER This invention relates to surface grinders wherein a workpiece to be ground is mounted on and secured to a horizontally reciprocated table by which the workpiece is carried back and forth under a rotating grinding wheel, in work performing engagement therewith; and the invention is more particularly concerned with means for controlling the traverse of the table.

The work carrying table in such a surface grinder is caused to reciprocate by reversible power means, and reversal of its direction of travel is automatically efiected by control means which also serve to determine the length of its stroke. Heretofore, the control means included, as an essential part thereof, a pair of trip dogs or abutments that were movable with the table to collide with reversing control means located at a fixed position on the stationary structure of the machine. Each such collision effected reversal of the power means. To enable the length of the stroke to be changed, the trip dogs or abutments that moved with the work carrying table were adjustable lengthwise of the table and with respect to one another.

The trip dogs were releasably held in place on the table by means of clamping screws which had to be loosened and retightened to permit the trip dogs to be reset for a new stroke length adjustment. Hence it was impossible, for all practical purposes, to adjust the stroke while the machine was in opera tion and the table was moving.

Another and very serious disadvantage of this prior arrangement was that the frequent and constantly repeated collisions or other physical engagements between the trip dogs and the reversing control means imposed mechanical wear upon them that eventually led to failure.

By contrast, it is an object of the present invention to enable the stroke length of such a table to be safely and easily ad justed while the table is in motion.

The present invention achieves this significant and important objective through the provision of a control system which is governed by cooperating movable and stationary actuator means of which the movable actuator means comprises a single unit or device connected with the work carrying table to move in unison therewith along a defined path, while the stationary actuator means comprises a pair of units or devices that are connected with the power means, each adjustably fixed to a stationary part of the machine adjacent to the path of the movable actuator means.

Another and very important object of this invention is to provide reciprocation control means for the work carrying table of a surface grinder or the like which does not rely upon collision or physical contact between the elements of the control mechanism for effecting reversal of the table actuating power means, but which instead efi'ects reversal of the direction of table motion in response to mere proximity to one another of the cooperating parts of the control means.

With these observations and objectives in mind, the manner in which the invention achieves its purpose will be appreciated from the following description and the accompanying drawings, which exemplify the invention, it being understood that such changes in the specific apparatus disclosed herein may be made as come within the scope of the appended claims.

The accompanying drawings illustrate several complete examples of embodiments of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

FIG. 1 is a perspective view of a surface grinder incorporating an embodiment of the principles of this invention;

FIG. 2 is a top view, with parts shown broken away and in section, of the front portion of a surface grinder like that shown in FIG. 1, incorporating an embodiment of the invention in which physical contact between the movable and stationary actuator means effects reversal of the table reciprocating power means;

FIG. 3 is a cross sectional view taken on the plane of the line 3-3 in FIG. 2;

FIG. 4 is a sectional view taken on the plane of the line 4-4 in FIG. 3;

FIG. 5 is a perspective view illustrating a modified embodiment of this invention, wherein the reversing control means comprises reed switches responsive to adjacent permanent magnets and wherein reversal of the direction of table motion is efiected without physical contact between the elements of the reversing control means;

FIG. 6 is a cross sectional view on the plane of the line 6-6 in FIG. 5;

FIG. 7 diagrammatically illustrates, in simplified form, a hydraulic power system for reciprocating the work carrying table;

FIG. 8 diagrammatically illustrates, also in simplified form, a control circuit for the hydraulic power system of FIG. 7, cmploying the non-contacting type of reversing control means shown in FIGS. 5 and 6;

FIG. 9 is a top view of another embodiment of the invention, wherein the cooperating means for governing the direction of table motion is responsive to proximity between the movable and stationary actuator means and utilizes photosensitivity to effect its controlling function;

FIG. 10 is an end view of the structure shown in FIG. 9;

FIG. 11 diagramatically illustrates a sonically responsive embodiment of the invention wherein proximity between the movable and stationary actuator means is utilized to effect the desired reversal of table motion; and

FIGS. 12 and 13 diagrammatically illustrate a pneumatically responsive means for utilizing proximity between the movable and stationary actuator means to effect the desired reversal of table motion.

Referring now to the accompanying drawings, the numeral 5 designates generally a surface grinder of relatively conventional design having a base 6 upon which a work carrying table 7 is mounted for endwise horizontal reciprocation. Also mounted on the base, behind the table, is an upright column 8 in which a slide 9 is mounted for vertical adjustment. A rotatably driven grinding wheel 1 l is joumalled on the slide 9, positioned over the table 7. Hence, workpieces secured to the table by means of a magnetic chuck (not shown) or otherwise, will be carried back and forth under the grinding wheel as the table reciprocates.

Proper work performing engagement between the grinding wheel and the work pieces on the table necessitates vertical adjustment of the slide 9, which is effected by conventional downfeed mechanism controlled by a hand wheel 12; and to enable the grinding of a surface that is wider than the grinding wheel, the column 8 is transversely indexed by conventional crossfeed mechanism controlled by a hand wheel 13.

The grinding wheel is of course driven by a suitable motor which, in the grinder illustrated in FIG. I, is of the hydraulic type.

The reciprocation or traverse of the work table with which this invention is primarily concerned is effected by a hydraulic cylinder 14 located under the table and having its piston drivingly connected with the table. Fluid pressure is fed to the cylinder to effect transverse of the work table first in one direction and then the other as determined by a control system which includes cooperating movable and stationary actuator means. The movable actuator means is connected with the table to travel therewith in a defined horizontal path, and the stationary actuator means is adjustably fixed to a stationary part of the machine.

A simplified diagrammatic illustration of the control system is shown in FIGS. 7 and 8, and reference to these views at this 7 time will be helpful to an understanding of the invention. As

FIG. 8 illustrates in very simplified form one arrangement by which the solenoids A and B can be momentarily energized to effect reversal of the power means, i.e., the cylinder 14. As here shown, energization of the solenoid A is controlled by a relay 16 which is in turn controlled by a reed switch 17, and energization of the solenoid B is controlled by a relay 18 which is controlled by a reed switch 19. The reed switches are biased to their closed positions but are normally held open by permanent magnets 20.

The reed switches and their companion permanent magnets constitute the aforementioned stationary actuator means. The cooperating movable actuator means is simply a vane 22 of magnetically permeable iron that is fixed to the table and travels therewith along a defined straight path that carries the vane between the reed switches and their companion permanent magnets. There is, of course, no contact between the vane and the magnets or the reed switches. The mere interpositioning of the vane between a reed switch and its magnet is sufficient to overcome the attraction of the magnet upon the switch and, as a result, the switch closes, energizing its connected relay, which in turn closes an energizing circuit to the appropriate valve solenoid and thus effects reversal of the table motion. As soon as this takes place, the vane is carried out of proximity to the just-closed switch and allows the switch to reopen.

To enable manual energization of either of the solenoids, a push button switch PB may be connected in parallel with each of the reed switches.

The magnet-reed switch arrangement for controlling energization of the solenoids, as diagrammatically illustrated in FIG. 8, constitutes the preferred embodiment of the invention.

Its structural aspects are shown in FIGS. and 6. As there depicted, a stationary part 25 of the machine, which may be part I of the base 5, has an elongated rail 26 mounted thereon in parallel spaced relation to a portion 27 of the table or a part fixed thereto. Slidably mounted on the rail are the two reed switches and their companion magnets. Each reed switch is suitably encapsulated in a housing 29, and that housing and the permanent magnet associated with the switch are fixed to a bracket 30 upon which there is a shoe 31 that rides on a portion of the rail. The bracket 30 also has a downwardly directed arm 32 which overhangs the rail at the side thereof opposite the shoe and through which a clamping screw 33 is threaded. The head of the screw 33 is formed as a knob 34 by which the stationary actuator means can be adjustingly moved along the rail and by which the screw can be readily turned for releasing and securing the bracket so that it can be clamped to the rail in any position along the length thereof. This enables the length of the stroke of the table to be safely and easily adjusted while the machine is in operation and the table is in motion.

As shown in FIG. 6, the iron vane 22, which passes between the magnets and their respective reed switches at the ends of the table stroke, is fixed to a member 27 which moves with the table and which may in fact be a part of the table itself.

Flexible, coiled conductors 35 lead from the encapsulated reed switches to connect them into the control circuit diagrammatically shown in FIG. 8.

As will be readily appreciated there is a distinct advantage in the absence of any need for physical contact between the movable and stationary actuator means in the reed switchmagnet arrangement for controlling the energization of the solenoids that govern the shifting of the direction control valve of the hydraulic system. FIGS. 9-13 illustrate three other possible alternatives for the magnet-reed switch arrangement, all of which are proximity responsive.

In FIGS. 9 and 10, the controlling function is accomplished photosensitively, by interrupting a light beam at each end of the table traverse. For this purpose, a light source 38 and a photosensitive sensor 39 respectively replace the magnet and the reed switch, controlling the circuit in the same general manner; and an opaque barrier 37 travels with the table to move between them at the end of the stroke.

In FIG. 11, an ultrasonic sound beam 40 is emitted by a transmitter 41 toward a receiving sensor 42. The receiving sensor energizes a control relay 43 until a barrier travelling with the table interrupts the beam 40.

FIGS. 12 and 13 illustrate the use of fluidic devices 45 as the adjustable stationary actuator means. As seen in FIG. 12, air is blown outwardly through the convergent outer passages of the stationary actuator means, and when the interrupting vane 46 is not in proximity to the fluidic device, an air flow in the same direction is drawn through its center passage. But when the barrier is present, it deflects back into the center passage the air flowing from the other two passages and develops a back pressure in the center passage which is utilized to actuate a suitable pressure responsive switch 47, to effect the desired valve spool shift.

Although the non-contacting embodiments of the invention have a distinct advantage over physically contacting actuator means, the invention can be embodied in that form as shown in FIGS. 2, 3 and 4. In this case, a rotating type of control valve 50 is mounted in the front portion of the machine and is suitably connected with the hydraulic system by which the table traverse is produced. The valve can be manually actuated by a lever 51 which swings generally parallel to the rotational axis of the valve and which is connected with the rotor of the valve through a Scotch yoke 52. Of course the valve is also automatically actuated at the ends of the table traverse.

For its automatic operation the valve rotor is connected with a coaxial rotatably mounted rod 53 which extends in the directions of motion of the table. Slidably splined to the rod are two collars 55, from each of which a pin or abutment 56 projects into the path of a generally trapezoidal cam 57 which is fixed to a portion 58 of the table. When the cam engages one of the pins 56, the rod 53 is rotated in one direction, and its engagement with the other pin rotates the rod in the opposite direction. In this manner, the rotor of the control valve is actuated to direct pressure fluid first into one end of the cylinder 14 and then the other.

Extending parallel to the rod 53, in front of it, is a rail 54 which is fixed to a stationary part 55 at the front of the machine.

Each of the collars is embraced by the arms of a yoke 60 which rides along the rail 54 and which may be clamped to the rail at any point along its length by means of a clamping screw 61. It will be apparent that shifting of either yoke 60 along the rail 54 will eflect adjustment along the rod 53 of the collar embraced by the yoke, and that tightening of the clamping screw 61 for the yoke fixes the position of its collar.

From the foregoing description taken with the accompanying drawings it will be apparent that this invention provides means for controlling reciprocation of the work carrying table of a surface grinder or similar machine whereby the stroke of the table can be adjusted while the machine is in motion, and it will be further apparent that the invention also provides control means for such a table that has an extremely long useful life by reason of the fact that there is no physical contact between the cooperating fixed and stationary elements of the table control apparatus.

Those skilled in the art will appreciate that the'invention can be embodied in forms other than as herein disclosed for purposes of illustration.

The invention is defined by the following claims.

I claim:

1. In a machine tool wherein work is performed by repeated contact between a work performing element and a workpiece on a work carrying element in consequence of reciprocation of one of said elements with respect to the other and the stationary structure of the machine, wherein such reciprocation is effected by reversible power means governed by manually adjustable control means which automatically effects reversal of said power means and sets the length of the stroke of said reciprocated element,

the improvement by which adjustment of the control means may be easily and safely made while the machine is in operation and without stopping reciprocation of said reciprocated element, and which improvement comprises:

A. cooperating movable and stationary actuator means,

the former being movable with the reciprocated element along a defined path, and the latter being on a stationary part of the machine adjacent to said path, and comprising a pair of spaced apart actuator devices adjustably fixed to said stationary part of the machine for adjustment lengthwise of said defined path to any selected spacing, which spacing determines the length of the stroke of the reciprocated element;

B. electrically energizable translating means for effecting reversal of said power means; and

C. electric switch means controlling energization of said translating means, said switch means being maintained in one of two positions by the attractive effect of a permanent magnet in juxtaposition thereto, said switch means and the permanent magnet constituting one of said cooperating actuator means, and the other of said actuator means being ferro-magnetic means and which occupies a position between said permanent magnet and the switch means when the movable and stationary actuator means are in proximity to one another.

2. In a machine tool, the improvement set forth in claim 1, further characterized in that said switch means and permanent magnet constitute the stationary actuator means, and said ferro-magnetic means is the movable actuator means and comprises a ferromagnetic shield fixed to the reciprocated element and movable between one of the switch means and its companion permanent magnet as the reciprocated element reaches each end of its stroke.

3. A machine having a work performing element and a workpiece carrying element, one of which is reciprocable relative to the other, reversible power drive means for said one element by which the same is repeatedly reciprocated, a reversing controller connected with the power drive means and having two conditions which respectively correspond to the directions of motion of the power drive means, and instrumentalities operatively associated with the reciprocable element and with the reversing controller for effecting automatic reversal of the direction of the stroke of the reciprocable element and by which the length of its stroke can be adjustably predetermined, wherein said instrumentalities are characterized by:

A. two separate two-position switches, each operatively connected with the reversing controller to maintain the same in one of its conditions when the switch is in one of its two positions and to cause the controller to assume its opposite condition when the switch is moved to its other position,

each of said switches being biased to one of its two positions;

B. switch actuating means for each of said two switches, each of said switch actuating means comprising physically spaced apart energy producing and energy responsive elements which coact when the space therebetween is uninterrupted to maintain the switch controlled thereby in its position opposite that to which it is biased while allowing the switch to be moved to its opposite position by the bias thereon when the space between said elements is interrupted;

C. movable blocking means positionable between said physically spaced elements to interrupt the space therebetween, said blocking means being constrained to move with the reciprocable element along a fixed path; and

D. means mounting said switch actuating means on a stationary part of the machine in positions adjacent to the path traversed by said blocking means in its reciprocation with said reciprocable element and providing for adjustment along said path independently of one another, but

otherwise maintaining them in locations fixed with respect to the stationary parts of the machine,

with said physically spaced apart elements at opposite sides of and spaced from the path of said blocking means.

4. The structure of claim 3, wherein said switches are of the magnetically actuated reed type, and the energy producing element is a permanent magnet,

and wherein said blocking means is a ferromagnetic member.

5. The structure of claim 3, wherein said switches are photosensitively responsive, and the spaced energy producing and energy responsive elements of the switch actuating means are a light source and a photosensitive sensor.

6. The structure of claim 3, wherein said switches are sonically responsive, and the spaced energy producing and energy responsive elements of the switch actuating means are a sound transmitter and a sound receiving sensor,

wherein a relay energized by the receiving sensor maintains the associated switch in the position to which it is biased until the sound beam between the transmitter and receiving sensor is interrupted,

and wherein said blocking means comprises a sound barner.

7. The structure of claim 3, wherein said switches are maintained in the position opposite that to which they are biased by a pressurized stream of air until a barrier vane which constitutes said blocking means interrupts the air stream. 

1. In a machine tool wherein work is performed by repeated contact between a work performing element and a workpiece on a work carrying element in consequence of reciprocation of one of said elements with respect to the other and the stationary structure of the machine, wherein such reciprocation is effected by reversible power means governed by manually adjustable control means which automatically effects reversal of said power means and sets the length of the stroke of said reciprocated element, the improvement by which adjustment of the control means may be easily and safely made while the machine is in operation and without stopping reciprocation of said reciprocated element, and which improvement comprises: A. cooperating movable and stationary actuator means, the former being movable with the reciprocated element along a defined path, and the latter being on a stationary part of the machine adjacent to said path, and comprising a pair of spaced apart actuator devices adjustably fixed to said stationary part of the machine for adjustment lengthwise of said defined path to any selected spacing, which spacing determines the length of the stroke of the reciprocated element; B. electrically energizable translating means for effecting reversal of said power means; and C. electric switch means controlling energization of said translating means, said switch means being maintained in one of two positions by the attractive effect of a permanent magnet in juxtaposition thereto, said switch means and the permanent magnet constituting one of said cooperating actuator means, and the other of said actuator means being ferro-magnetic means and which occupies a position between said permanent magnet and the switch means when the movable and stationary actuator means are in proximity to one another.
 2. In a machine tool, the improvement set forth in claim 1, further characterized in that said switch means and permanent magnet constitute the stationary actuator means, and said ferro-magnetic means is the movable actuator means and comprises a ferro-magnetic shield fixed to the reciprocated element and movable between one of the switch means and its companion permanent magnet as the reciprocated element reaches each end of its stroke.
 3. A machine having a work performing element and a workpiece carrying element, one of which is reciprocable relative to the other, reversible power drive means for said one element by which the same is repeatedly reciprocated, a reversing controller connected with the power drive means and having two conditions which respectively correspond to the directions of motion of the power drive means, and instrumentalities operatively associated with the reciprocable element and with the reversing controller for effecting automatic reversal of the direction of the stroke of the reciprocable element and by which the length of its strokE can be adjustably predetermined, wherein said instrumentalities are characterized by: A. two separate two-position switches, each operatively connected with the reversing controller to maintain the same in one of its conditions when the switch is in one of its two positions and to cause the controller to assume its opposite condition when the switch is moved to its other position, each of said switches being biased to one of its two positions; B. switch actuating means for each of said two switches, each of said switch actuating means comprising physically spaced apart energy producing and energy responsive elements which coact when the space therebetween is uninterrupted to maintain the switch controlled thereby in its position opposite that to which it is biased while allowing the switch to be moved to its opposite position by the bias thereon when the space between said elements is interrupted; C. movable blocking means positionable between said physically spaced elements to interrupt the space therebetween, said blocking means being constrained to move with the reciprocable element along a fixed path; and D. means mounting said switch actuating means on a stationary part of the machine in positions adjacent to the path traversed by said blocking means in its reciprocation with said reciprocable element and providing for adjustment along said path independently of one another, but otherwise maintaining them in locations fixed with respect to the stationary parts of the machine, with said physically spaced apart elements at opposite sides of and spaced from the path of said blocking means.
 4. The structure of claim 3, wherein said switches are of the magnetically actuated reed type, and the energy producing element is a permanent magnet, and wherein said blocking means is a ferromagnetic member.
 5. The structure of claim 3, wherein said switches are photosensitively responsive, and the spaced energy producing and energy responsive elements of the switch actuating means are a light source and a photosensitive sensor.
 6. The structure of claim 3, wherein said switches are sonically responsive, and the spaced energy producing and energy responsive elements of the switch actuating means are a sound transmitter and a sound receiving sensor, wherein a relay energized by the receiving sensor maintains the associated switch in the position to which it is biased until the sound beam between the transmitter and receiving sensor is interrupted, and wherein said blocking means comprises a sound barrier.
 7. The structure of claim 3, wherein said switches are maintained in the position opposite that to which they are biased by a pressurized stream of air until a barrier vane which constitutes said blocking means interrupts the air stream. 